Preference
I talked about this with a guy who has bought/sold guns for over 40 years. While I do like the tang safety of the Mossberg, the aluminum receiver is not as strong as steel if you are going to shoot the gun A LOT! You know, hunting, claybird practice, trap, skeet, sporting clays. For a gun you are going to shoot, shoot, shoot, I would favor the 870. I keep hearing how Remington is going downhill, so that may be a factor. If I was getting an 870, I would buy used from the guy I mentioned in the first sentence. I have a very old Ithaca m 37, so I don't really need another pump, unless I wanted to deer hunt with it, and get a slug barrel (can't get one for the Ithaca, it's too old.)